报告人：张磊教授

        中国科学技术大学

题目：Positivity in characteristic p>0

时间：2018年01月23日上午10:40

地点：海韵数理楼661

报告摘要：It is known that for a fibration f: X --->Y over the field of complex numbers, the pushforward of relative (pluri)canonical sheaf is weakly positive. This famous result plays an important role in studying fibrations, say subadditivity of Kodaira dimensions. However, this is not true in positive characteristics by Raynaud’s example. In this talk I will introduce some reasonable formulations due to Patakfalvi and Ejiri, and explain Ejiri’s idea of the proof, which is quite simple but essential I think. His proof uses trace maps of relative Frobenius maps.

报告人简介：张磊，中国科学技术大学教授；2011年博士毕业于北京大学，2011年至2017年任教于陕西师范大学，从2018年开始任中国科学技术大学教授。张磊的研究方向是代数几何，研究内容涉及代数曲面，不规则代数簇以及特征p上的代数簇的分类，研究成果发表在 Compos. Math.，J. Lond. Math. Soc.，Math. Res. Lett., Proc. Amer. Math. Soc. 等杂志。

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